Selective plugging of gas-injection oil wells in oil field gas-drive projects



Z GDBQU BAIL AL.

Oct 8, 1957' szzscnvs PLUGGING or GAS-INJECTION on.

IN 011., FIELD GAS-DRIVE, PROJECTS Filed July 8, 1953 Wire. "he

Lubricdfor WW/ :iw1:12:22352 15: ttliti:I .85 9

Recording orifiqe Casing .M B m mm B F. Grqnf Simon Kiosky ATTO ' tiontowards the surrounding recovery wells,

maintainthe recovery ofo'il; v .7 This is due to the fact that the gasiron: the input well .1 I more than through the oil-bearing strata.

-' 5 I mes sarcoma rwocmo or Gasman-i024 on.

warm neon. FIELD oAsoRrvr; rruurtc'rs rm '1'. Ball and ems. rem an...slim mo s Washington. o. 0., to the United- States of Americarepresented by the Secretary oi-the interior p Application July mass-sumrte- 55,59 6 Claims; got. 166-!) Patent-ed ()ct.v 8, 1957 (Granted nd"Title 35,11. 5. Code (1952 'm. 266) invention herein described andclaimed may be used by or for theGove'rnment of the United States ofAmerica for governmental purposes without. the payment I of royaltiesthereon or therefor.

This invention'reiates to a method of treat ing'und'er groundoil-producingforinations for thep v of increasing the recovery of 0Htherefrom. v

it is well known to inject gas, such asair, natural or other'gasespreviously recovered fi'orn other wells into underground oil-bearingformations for the purpose of increasing the recovery of oil therefrom.In such operations it is customary to inject the gas under pressurethrough a centrally located injection well in the fQrmation '50 that thegas will drive the oil through the iorzua In most oil-bearing formationsthe oil in '5 pinrality of superimposed strata oi varyingpermeabilities,

stream of'wet gas so that a occult, which results in the formation asolid norganic smokes,

insoluble in both water and are immediately by-the-stream of injected:3: irto the adjacent underground strata and channel's.

Liquids suitable for this purpose are silicon metrichlorid, (B. P, 57.6C.) titanium tetrachloride, (B. B. 136.4. c. and tin tetrachloride, a.2; 114.1 c; allof which are chlorides of elements'ocamin; in the fourthgroup oi'the periodic table and tanning tetrachloride:

which boil belowaboutj 140- C., but rea'dilywolhtilize in a streamofgas. 'l1xis group oftdnchlorides does not include carbon tetrachloride,(8. P, 76.3 C.) which is not suitable for our purpose.

Of this group, titanium re is the preferred material and itsdecomposition at I: gas may be represented by the equations' In theaccompanying drawings, F155. 1 and 2, we have illustrated one method ofcarrying out our invention,

7 In Fig. l, the character 1 refers to a wire line, which is used tolower the bomb 2, containing the liquid tetrachloride, through thelubricator 3, the tubing 4, and the and when'gas is'injccted into ther'orma'tiog'ofl will be' recovered for a certain length of timewithoutthe injeo tion of abnormal quantities of'gas. As the recovery of oilproceeds,1bowe ve'r, the fiow'ofgas from the input well increases and alarger quantityof ai'r must bes'npplied to I quickly displaces the oil'from the more permeablefstrata, leaving open channels through which theinjected gas may p The present invention providesfan improvedmethodoftreating underground oil-bearing formation in which bypassing-ofthe injection gas is diminished; with a com?- sponding increase inuseiulrworlt in expelling oil from the adjacent stratawith' an increasein the volume of oil recovered per unit of gas injected. 4 x

A further object of the invention is to produce in the injection gas adispersed finely divided. solid, which is insoluble in both water andoil, and which,according to currently held theories, deposits in themore permeable strata of the formation thereby'avoiding or minimizingthe by-passing of the least permeable strata. .Regardless of the theory,however, we have foundthat our'rnethod is effective to increase recoveryof oil per unit of-gas injected.

While some of the-metallic chlorides mentionedherein have previouslybeen employed for the pluggin'gof oil wells, by injection in the form ofpure liquids or oil suspensions none of them have been applied in the.form of'srnokes as described hcreim Furthermore, they ,were deposited inthe form of gelatinous precipitates and their valve 5. into the well.Smallermhe' S serves to admit air from-the compressor (not shownlmd itsvolume and pressure are continuously recordcl'og the meter 7. In Fig.Lthebomb' 2 is shown loweiui to the bottom-of the well and resting onthe anchor 8. When the wire line 1 is pulled upwardly the liquidtetrachloride in the I bomb 2 is forced through the porous cyiinder 9"and evaporates into the stream of wet air, forced down thetubing by thecompressor. whereupon, ibenpors of the tetra chloride react with themoisture in the aires indicated in the equation above, forming soliddioiide smoke and hydrogen chloride, whicliare carried into the oilbearing strata, through the openings 11. The packer 12 prevents thegenerated smoke from escaping upwardly through In tests made on the sizeofth e moie'particlcs formed irom titanium tetrachloride inthis-fzs'm'on it was found that they were .withinthe limits of l to 10microns.

In an actual test made in an oil well in Pennsylvania, it;

, was found that after evaporation of 1500 cc. of liquidtitaniumtetra'chloride, the average iniection rate dropped from 28,000C.'F./day to 13,800 C. I-Jday. In a zeoond well, in which. 700 cc. oftitanium tetrachloride were evaporated, in the manner dcscnoed, thegas-injection rate Y dropped from 19,600 C. F. /day to 7,300 C. FJday.The

action in this case was-not selective, Their main purpose in these caseswas to prevent water from seeping into the well. 1 By applying thepresent method to both depleted and .producing' strata, both objects maybe efiected' to some degree, but reduction in the volume of gas injectedper barrel of oil recovered will still result because the new of gasthrough-the more permeable strata is ruluced much According to onemodification of the present invention,

corresponding recoveries of oil, in a producing well, located bet-weenthe two plugged wells, after a temporary drop after plugging, changedfiom Z5 b- L/wk. to 3.0

bbL/wk. 1

This corresponds to auchange in gzsfiuid ratio from 50,000 to 26,000after a temporary rise, or an indicated improvement of nearly percent onthe volume of injected air.

It is desirable, although not absolutely necessary, to

evaporate ammonium hydroxide in the same manner and pass it out into theadjacent formation, thereby neutralizing the hydrogen chloride formed inthe tubing and still present in the near-by formation.

While the above description reprexaz one form of the invention it is notthe only way it may be carried out. and the scope of our invention islimited only by the following claims.

We claim:

1. 1n the recovery of oil from node-pound oil-bearutilit 1 I ingiqrmat-i-ons by gas-injection drive, the imprpement which comprisesvaporizing in a stream of moisture-can? taining gas, the tetrachloride.of aneleme nt oi the git mp consisting of silicon, titanium, and tin,admixing said ietrachloride in the vapor statewith said moisturecontaining gas, {hereby causing said t'etraeblgride 1;: met with themoisture in said gaswith the resultant formation sf a smoke comprisingfinelydivided solid patficles, fore:

m at least partially plugged and the. injectioh rate of ing theresultant smeke into the shrrouncling formation,

whereby the more permeable portions of said formation gas imo the said'formation is substantially lowered, and

recovering oil irom said oil-bearingv formatibn bysgid gasinjection drive. r 2. The'methqd of claim 1 in which the tetrachloride is vaporizedwithin the well.

3. The method of claim i in which a volaiile base is injectedsubsequent. U; the smoke formation to neutralize w the acid liberatedduring srnqke formation.

4;. 111;- method orda n 1-121 which the mama: em played is titaniumien-ae'nlcride.-

S. The meihod of claim l in which the chloride employed'is' silicontetrachloride. v

'6. Them emodofdaimlinwhiehtheahloridcmplayed is fin m cum mim in thefile a: pawn:

smrss PATENTS McPherson c! 211.: Chemistry, pub. by Ginn, 1940, pp. 421,430, 431, -685, Copy in Scientific hlarary.

1.IN THE RECOVERY OF OIL FROM UNDERGROUND OIL-BEARING FORMATIONS BY GASINJECTION DRIVE, THE IMPROVEMENT WHICH COMPRISES VAPORIZING IN A STREAMOF MOISTURE-CONTAINING GAS, THE TETRACHLORIDE OF AN ELEMENT OF THE GROUPCONSISTING OF SILICON, TITANIUM, AND TIN, ADMIXING SAID TETRACHLORIDE INTHE VAPOR STATE WITH SAID MOISTURE CONTAINING GAS, THEREBY CAUSING SAIDTETRACHLORIDE TO REACT WITH THE MOISTURE IN SAID GAS WITH THE RESULTANTFORMATION OF A SMOKE COMPRISING FINELY DIVIDED SOLID PARTICLES, FORCINGTHE RESULTANT SMOKE INTO THE SURROUNDING FORMATION, WHEREBY THE MOREPERMEABLE PORTIONS OF SAID FORMATION ARE AT LEAST PARTIALLY PLUGGED ANDTHE INJECTION RATE OF GAS INTO THE SAID FORMATION IS SUBSTANTIALLYLOWERED, AND RECOVERING OIL FROM SAID OIL-BEARING FORMATION BY SAID GASINJECTION DRIVE.